1. Field of the Invention
The present invention relates to a device to perform cruise control of the own vehicle while recognizing another vehicle traveling in front.
2. Description of the Related Art
Conventionally a technique is known, enabling cruise control of the own vehicle so as to follow another vehicle traveling in front (hereinafter this may be called a front vehicle) while recognizing the position or the speed of the front vehicle with an object detection unit thereof having a radar, a camera or the like.
A device performing this type of cruise control may cause a lost state in some cases, in which when the front vehicle travels while corning along a curve, for example, such a front vehicle may deviate from the detection target area (e.g., shooting area of the camera or searching area of the radar) of the object detection unit installed in the own vehicle and so the object detection unit fails to detect (loses) the front vehicle.
To cope with such a situation, JP 2004-206267 A (hereinafter called Patent Literature 1) and JP H7-76237 A (hereinafter called Patent Literature 2), for example, describe a technique of estimating the position or the speed of a front vehicle for cruise control of the own vehicle.
Patent Literature 1 describes a technique of, when a lost state occurs so that a front vehicle cannot be detected by its object detection unit, calculating the radius of the curve based on information detected with a steering sensor and a yaw rate sensor, and estimating the current position of the front vehicle using such a radius of the curve, or estimating the current position of the front vehicle using a past position of the front vehicle or the like.
Patent Literature 2 describes a technique of, when a lost state occurs so that a front vehicle cannot be detected by its object detection unit, of estimating the speed of the front vehicle (relative speed with reference to the own vehicle) by extrapolation based on the past speed data of the front vehicle.